The much-delayed security strategy is due to be unveiled on Wednesday, and is understood to identify a series of threats to the UK including water and energy shortages, cyber-terrorism and natural disasters.

Based on the US president's national security council, the new body will be staffed by senior politicians including, potentially, individuals from other parties, intelligence and military chiefs, and scientific experts.

The council is designed to complement rather than replace the existing ad hoc Cobra emergency committee, which was last convened by the Prime Minister to deal with this month's storms.

Lord Ashdown, the former leader of the Liberal Democrats, has been suggested as a possible leading opposition figure with the experience to be invited to serve alongside senior Government ministers.

Senior officials from the Home Office, Foreign Office, Ministry of Defence and Department for International Development will also sit on the council to ensure the foreign and domestic policy implications involved in the response to any emergency are given full consideration.

In an interview on BBC1's Politics Show, Lord West, the security and counter-terrorism minister, said the four-month delay in making the policy public was a result of the complex nature of the threats facing Britain.

They include human and animal diseases, from pandemic flu to the blue tongue virus, disasters following extreme weather events, and computer hacking with serious economic implications.

Lord West, who is a former First Sea Lord, denied the Government's approach to security lacked focus. He said: "Rather than anything in the past which was produced … we are now much more looking at the citizen and tying the citizen into this.

"Let's think of their vigilance, how does this involve them? We have to do that because they all interrelate. These things do need to be addressed holistically."

"If there was an easy answer to all of this we would not have had to go down this route. It is highly complicated and it is very difficult … but we are leading the world on this."

Sir Jeremy Greenstock, the UK's former ambassador to the United Nations, said the strategy would be too vague and undermined by funding cuts. Nick Clegg, the Liberal Democrat leader, said: "Expectations will be high given the lengthy delay in production of this strategy.

"Most importantly, the strategy will be judged on whether it strikes the right balance between security and liberty."

The review is expected to consider calls for an extension of the surveillance powers of MI5, amid revelations that the security services are demanding access to electronic travel documents.

David Davis, the shadow home secretary, described as "extraordinary" claims that MI5 want access to records relating to the Oyster smart cards used by 17?million Britons, and other private information held by the state.

A spokesman for the Office of the Information Commissioner confirmed discussions had been held with the Government but refused to give details.

At present, the security services can demand the Oyster records of suspects to establish their whereabouts at relevant times, but they do not have routine access to the entire database.